The presence of residual monomer vinyl chloride in vinyl chloride-base polymers and copolymers gives rise to disadvantages, among which the following may be mentioned; the danger of producing mixtures which detonate with the ambient air, the danger of contaminating the air in the plants where such polymers or copolymers are handled, and the danger of microballs being present in the finished articles prepared from such polymers and copolymers. Therefore, the attempt is made to reduce the proportion of residual monomer vinyl chloride therein to the minimum possible value.
When vinyl chloride-base polymers and copolymers are prepared in bulk, the resulting product, when the desired degree of conversion of the monomer composition is achieved, is a polymerisate which is subjected to a degassing treatment for separating the unreacted monomer composition from the polymers or copolymers which are produced in powder form.